Spectrometry device, liquid chromatograph, and wavelength calibration method of spectrometer

The wavelength of a spectrometer is calibrated by using a commercial Ho glass filter. The spectrometer includes a light source including a D2 lamp and not including a mercury lamp, and a reference wavelength input unit for inputting, as a reference wavelength, a wavelength of a specific absorption peak separately measured for an Ho glass filter to be used. To calibrate the wavelength of the spectrometer by using the wavelength of a specific emission line peak of the D2 lamp and the reference wavelength input by the reference wavelength input unit, the wavelength calibration unit holds a conversion table showing a theoretical relationship between the number of control pulses for rotating a diffraction element and the corresponding wavelength of diffracted light, and calibrates the number of control pulses from the conversion table by the wavelength calibration unit.